New records of the hypercalcified sponge Plectroninia (Calcarea, Minchinellidae) in the Recent deep ocean

Numerous small specimens of hypercalcified sponges of the genus Plectroninia (Jurassic to Recent) are recorded from deep water in the Atlantic, Indian and Pacific oceans, where they are attached to diverse hard substrata, mostly scleractinian skeletons. Being represented as skeletons of linked calcareous tetractines with an incomplete free spicule complement, the specimens could not be identified at the species level. These observations show that Plectroninia spp. have a wide distribution in the bathyal zone of the Recent World Ocean, where they may be the most common calcareous sponges.